70 
SOIL SURVEY OF BUFFALO COUNTY. 
September, inclusive. June has the heaviest rainfall, averaging 
4.1 inches, while July averages 4 inches and May 3.9 inches. 
The precipitation during the winter, on the other hand is slight; 
December, January, and February each averaging from 1 to 1.5 
inches of rain and melted snow. The average rainfall for 
the state during the winter is 3.9 inches, during spring 8.3 
inches, during summer 11.4 inches and during autumn 7.4 inches. 
Most of the rainfall occurs just preceding and during the 
period of plant growth, thus being received by the .crop at the 
most effective time. Wisconsin receives during the growing sea¬ 
son, April to September, inclusive, an average of 21 inches, which 
is as much rain as is received during the same months by eastern 
Texas, Illinois, Ohio, or eastern New York. The small winter 
precipitation in Wisconsin, mostly in the form of snow, on the 
other hand, causes virtually no leaching of fertility from the soil, 
or erosion. 
Another phase of rainfall distribution of great importance 
is its variation within a period of a few weeks. Frequently 
periods of drought and periods of unusually heavy rainfall occur, 
continuing for from one to four weeks, and occasionally longer. 
Observations taken at Madison over a period of 30 years, from 
1882-1911, inclusive, show that there are, on the average, three 
ten day periods during each growing season when the amount 
of rainfall is so slight that crops on a reasonably heavy soil 
(Miami silt loam) actually suffer from the lack of moisture. 
Buffalo County lies partly within the Mississippi Valley and 
partly within the Southern Highlands, which are recognized as 
forming two of the eight climatic provinces in Wisconsin. The 
Mississippi Valley is a rather deep depression, the warm influenc.e 
of the lower altitude being apparent from Dubuque, Iowa, as 
far north as Grantsburg, Wis. This narrow valley is much 
cooler and has drier winters than the Lake Michigan shore. The 
mean summer temperature averages about 78° F., and is similar 
to that of New Jersey, southeastern Pennsylvania, Ohio, or 
southern California. The mean winter temperature in the north¬ 
ern part of this valley resembles that of northern Vermont, 
northern Michigan, or eastern Montana. On an average of seven 
days during the winter the thermometer drops to -10° F. or 
lower, while during summer afternoons a temperature of 95° 
may be expected. The growing season in this valley ranges from 
150 to 175 days, about the same duration as that of the Hudson 
